Aneurysms can be complicated and difficult to treat. For example, treatment access may be limited or unavailable when an aneurysm is located proximate critical tissues. Such factors are of particular concern with cranial aneurysms due to the presence of brain tissue surrounding cranial vessels.
Prior solutions have included endovascular treatment access whereby an internal volume of the aneurysm sac is removed or excluded from arterial blood pressure and flow.
Alternative to endovascular or other surgical approaches can include occlusion devices. Such devices have typically incorporated multiple embolic coils that are delivered to the vasculature using microcatheter delivery systems. For example, when treating cranial aneurysms, a delivery catheter with embolic coils is typically first inserted into non-cranial vasculature through a femoral artery in the hip or groin area. Thereafter, the catheter is guided to a location of interest within the cranium. The sac of the aneurysm can then be filled with the embolic material to create a thrombotic mass that protects the arterial walls from blood flow and related pressure. One particular type of occlusive approach endeavors to deliver and treat the entrance or “neck” of the aneurysm as opposed to the volume of the aneurysm. In such “neck” approaches, by minimizing blood flow across the neck, then a venostasis in the aneurysm may be achieved. In turn, a thrombotic mass may naturally form without having to deliver embolic materials, as previously described. This is preferable to masses formed from embolic material since a natural mass can improve healing by reducing possible distention from arterial walls and permits reintegration into the original parent vessel shape along the neck plane of the aneurysm. It is understood that the neck plane is an imaginary surface where the inner most layer of the parent wall would be but for the aneurysm. However, neck-occlusive approaches are not without drawbacks. It is typical for neck-occlusive approaches to fail to impede flow into blood vessels while also blocking the aneurysm neck in the parent vessel. This can unintentionally lead to severe damage if the openings of the vessels are blocked. Furthermore, embolic coils do not always effectively treat aneurysms as re-canalization of the aneurysm and/or coil compaction can occur over time.
Several embodiments of an occlusion device are described in U.S. Pat. No. 8,998,947. However, this approach relies upon the use of embolic coils or mimics the coil approach to obtain a safe packing density and therefore unnecessarily risks rupture of the aneurysm. Furthermore, this approach fails to teach a delivery system whereby an occlusion device can be re-positioned after initial positioning of its aneurysm occlusion structure to ensure patient safety associated with precise positioning.
It is therefore desirable to have a device which easily, accurately, and safely occludes a neck of an aneurysm or other arterio-venous malformation in a parent vessel without blocking flow into perforator vessels communicating with the parent vessel.